Author
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Cundiff, Larry |
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Submitted to: Meeting Proceedings
Publication Type: Proceedings Publication Acceptance Date: 1/14/2006 Publication Date: 1/6/2006 Citation: Cundiff, L.V. 2006. The impact of quantitative genetics on productive, reproductive and adaptive traits in beef cattle. Proceedings Australian Beef - the Leader Conference. pp. 29-46. Interpretive Summary: Expected progeny differences (EPDs) have impacted genetic trends for growth traits and calving ease in most breeds of beef cattle. Recently EPDs for carcass traits have been introduced for 11 beef breeds. Research indicates that use of EPDs can be effective in changing marbling, fat thickness, and ribeye area in beef cattle. Research results are reviewed focusing on effects and utilization of heterosis and breed differences, and on the importance of matching genetic potential with consumer preferences and the climatic environment. Effects of heterosis increase production per cow about 20 to 25 percent in Bos taurus crosses (e.g., Angus X Hereford) and at least 50 percent in Bos indicus X Bos taurus breed crosses (e.g., Brahman X Shorthorn). Significant levels of heterosis are maintained by rotational systems of crossbreeding and in composite populations. No one breed excels in all traits of importance to beef production. Thus, crossing of two or more breeds can be used to optimize performance levels. In temperate environments, genetic potential for retail product and marbling are more nearly optimized in cattle with 50:50 ratios than in cattle with higher or lower ratios of Continental to British inheritance. To limit costs of production and improve efficiency of production a strong influence of tropically adapted germplasm is needed in subtropical and tropical environments. In the hotter and more humid climates of the U.S. Gulf Coast, about 50:50 ratios of Bos indicus to Bos taurus inheritance may be optimal. In harsher tropics, even higher levels of tropically adapted germplasm may be optimal. Use of F1 Brahman cross cows, Nellore, or Boran F1 cross cows or rotational crossing of composite breeds such as Beefmaster, Brangus, Bonsmara, or Santa Gertrudis are especially appropriate in subtropical environments. If replacement requirements for suitably adapted females are met and terminal crossing is feasible, then a Bos taurus breed can be used to optimize carcass and meat characteristics and increase market value of terminal cross slaughter progeny. In developing composite populations with an overall level of 50% tropical adaptation, it may be appropriate to substitute a portion (e.g., 25%) of non Bos indicus germplasm for Bos indicus germplasm from such breeds as the Tuli, Romosinuano, or Senepole to maintain tropical adaptation and improve meat tenderness, provided they are crossed with other breeds that optimize size and growth rate. Technical Abstract: No techncial abstract is required. |
